Capital Equipment News October 2017

“The efficiency of the screen determines the profitability of a plant (product on the floor). Poor screening efficiency can lead to excessive wear on all components in contact with material, and can also lead to damage to other processing equipment. Cost per tonne of product produced also increases.”

such sizing and has, in fact, supplied a number of these fine aperture screens in the past with no sizing issues.” Sandro Scherf, CEO of Pilot Crushtec International, says the screen is a more cost-effective change that can be done on a processing plant to make the operation more economical, considering the plant material flow. “The efficiency of the screen determines the profitability of a plant (product on the floor). Poor screening efficiency can lead to excessive wear on all components in contact with material, and can also lead to damage to other processing equipment. Cost per tonne of product produced also increases,” says Scherf. Evaluating screening technology There are several criteria used to evaluate screening technology, from separation effi- ciency and equipment durability, to overall maintenance costs and aftermarket support. According to Botha, from a milling perspective, it is of utmost significance that the screen be properly sized so that there won’t be any slurry pouring onto the screen oversize belt. “Reduced circulating loads also allow for more fresh feed into the milling circuit. Lower circulating loads also mean less wear in the system,” he says.

KEY TALKING POINTS

The efficiency of the screen determines the profitability of a plant

Finer aperture sizes used on standard vibrating screens require specialist sizing methods

Poor screening efficiency can lead to excessive wear on all components

Efficient screening ensures an accurate size range of material feed to the milling circuit

are more efficient when compared with cyclones in that less water will bypass to the oversize product and therefore carry less fines back to the mill. “The challenge, however, has always been finding a fine screening solution that can offer cut sizes in the 45 µm to 220 µm range, typically covered by hydrocyclones. For coarser primary mill product sizes, the obvious choice becomes a standard vibrating

screen where aperture sizes from 300 µm are now available,” says Botha. Botha adds that the finer aperture sizes used on standard vibrating screens do, however, require specialist sizing methods. “There have been a number of screens installed in recent times where the capacity has been incorrectly catered for, resulting in an undersized circuit. Osborn has the necessary expertise to provide

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